Oh multitasking. That staple of computing that got thrown out the window with many modern smartphones. We got some rudimentary thing in its place - but even as multitasking on phone and tablets improves, its user-visible side remains cumbersome. Windows 8 has a neat implementation, and now it's time Android follows in it footsteps.

App A has content that I want to compare to other content in App B. The best way to do that is to have them both visible at the same time. Anything else, wouldn't be as efficient (switching between them, transferring content between apps,etc).